In keeping with the global goal of health for all, the National Development Plan of Mexico describes health as a social right. To give effect to this right it is felt that the health sector must be restructured so as, among other purposes, to improve the coverage of services and strengthen the coordination of education institutions and social security agencies with health establishments, and to make the training of health personnel responsive to the country's real needs. No profession is better suited than nursing to the diversity of tasks in primary care. The authors describe the key role of this personnel in extending the coverage of health services to the entire population. They enumerate the range of basic--technical, administrative and educational--functions performed by nurses, and some factors that reinforce and others that restrict the contribution of nursing to primary health care in Mexico.